package com.verlet.springbootdemo.util;

import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

/**
 * @author verlet
 * @date 2021-03-17 18:21
 */
@Component
public class SpringContextUtils implements ApplicationContextAware {
    private static ApplicationContext applicationContext;

    /**
     * 实现ApplicationContextAware接口的context注入函数, 将其存入静态变量.
     */
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) {
        if (SpringContextUtils.applicationContext == null) {
            SpringContextUtils.applicationContext = applicationContext;
        }
    }

    /**
     * 取得存储在静态变量中的ApplicationContext.
     */
    public static ApplicationContext getApplicationContext() {
        checkApplicationContext();
        return applicationContext;
    }

    /**
     * 清除applicationContext静态变量.
     */
    public static void cleanApplicationContext() {
        applicationContext = null;
    }

    private static void checkApplicationContext() {
        if (applicationContext == null) {
            throw new IllegalStateException("ApplicationContext未注入,请在applicationContext.xml中定义SpringContextHolder");
        }
    }

    /**
     * 通过name获取 Bean.
     */
    @SuppressWarnings("unchecked")
    public static <T> T getBean(String name) {
        checkApplicationContext();
        return (T) applicationContext.getBean(name);
    }

    /**
     * 通过class获取Bean.
     */
    public static <T> T getBean(Class<T> clazz) {
        checkApplicationContext();
        return applicationContext.getBean(clazz);
    }

    /**
     * 通过name,以及Clazz返回指定的Bean。
     */
    public static <T> T getBean(String name, Class<T> clazz) {
        checkApplicationContext();
        return applicationContext.getBean(name, clazz);
    }
}